1. Field of the Invention
The present invention relates to an optical fiber fixing device for optically coupling an optical fiber with an optical communication module.
2. Description of the Related Art
In general, the optical communication module is constructed such that a laser diode, a lens and an optical fiber are combined and integrally formed to each other, the laser beams radiated from the laser diode are collected through the lens and optically coupled within the optical fiber.
A system in which the optical fiber can be inserted into or removed from the main body of the optical communication module is called as a receptacle type.
FIG. 11 is a partially sectional view for showing a configuration of an optical fiber fixing device 150 constituting the prior art optical communication module.
As shown in FIG. 11, the prior art optical fiber fixing device 150 is comprised of a cylindrical case 151, a substantially cylindrical sleeve 152 stored in the case 151 and a resilient metallic leaf spring 153.
The case 151 is provided with a front wall 154 having a circular fixing hole 154a. A side opposing against the front wall 154 of the case 151 is provided with a rear wall (not shown). In addition, the case 151 is provided with a side wall 151b connecting the front wall 154 with the rear wall.
The rear wall 151b is formed with an engaging step 155 projected inwardly between the front wall 154 and the rear wall at its inner circumferential surface. Then, the formation of the engaging step 155 causes a space between the front wall 154 and the engaging step 155 to become a space 156.
Then, at the root part of the engaging step 155 facing against a space opposite to the space 156 (the right side of the engaging step 155 shown in the figure) is formed a groove 157 extending along an inner circumferential surface of the side wall 151b.
A cylindrical sleeve 152 is formed with a fiber insertion hole 161 passing in the sleeve around its center. A part around the insertion hole 161 is applied as an external side wall 160 and its one end is formed with a flange-like knob 162 projected outwardly from the external side wall 160. In addition, the other end of it is formed with a metering section 163. Then, the end part of the knob section 162 of the external side wall 160 facing against the fiber insertion hole 161 is formed with a tapered part 161a.
A substantially central part between the knob 162 and the metering section 163 is formed with a stopper 164 protruded out of the external circumferential surface in an outward direction. Then, the sleeve 152 is stored in the case 151 and the knob 162 is protruded out of the fixing hole 154a of the case 151 in an outward direction.
At this time, the stopper 164 for the sleeve 152 is movably arranged and assembled within the space 156 between the front wall 154 and the engaging step 155.
The leaf spring 153 is comprised of a circular thin metallic base plate 165 and a substantially circular inner opening 166 recessed and formed at its central part. An edge part of the inner opening 166 of the base plate 165 is formed with a plurality of tongue-like resilient lock claws 167 formed to be extended inwardly.
These lock claws 167 are formed with their sectional surfaces being bent from the edge of the inner opening 166 at the base plate 165 on a plane of the base plate in the figure. On the other hand, the extremity end of each of the lock claws 167 is formed such that its sectional surface in a direction of plate thickness may form an acute angle.
Then, an entire circumferential edge of the base plate 165 at the leaf spring 153 is fitted to the groove 157 of the case 151, fitted and fixed there. At this time, the lock claw 167 is bent at its root part to face from the part of the inner opening 166 of the base plate 165 toward a side opposite to the front wall 154.
Next, the optical fiber 100 is comprised of a core 100a made of optical wave guide of glass or plastic material and the like and a clad 100b covering the core 100a with resin. Then, the optical fiber 100 is arranged within the sleeve 152 of the case 151. At the end part of the optical fiber 100 is arranged a laser diode (not shown) or the like. Then, the laser beam is incident from this laser diode to the end part of this optical fiber 100.
Then, a method for fixing the optical fiber 100 to the optical fiber fixing device 150 constructed as described above will be described as follows.
When the optical fiber 100 is inserted into the sleeve 152 from outside with the tapered portion 161a being applied as a guide, the optical fiber advances forward with its position being restricted by the fiber insertion hole 161, the extremity end of each of the lock claws 167 is pushed out in an inserting direction, a clearance between each of the extremity ends is widened and the optical fiber 100 is inserted smoothly into the case 151 while it is being abutted against the outer circumferential surface of the covering section 100b of the optical fiber 100.
Then, the covering part 100b of the optical fiber 100 is resiliently pushed by the extremity end of the lock claw 167.
However, in the case that a pulling-out force is applied to the optical fiber 100, i.e. a force for pulling out the optical fiber 100 from the case 151 is applied to the optical fiber 100, the extremity end of the stopper piece 167 formed in an acute angle bites into the outer circumferential surface of the covering part 100b so as to prevent the optical fiber from being pulled out of it.
With such an arrangement as above, laser beam incident to one end of the core 100a of the optical fiber 100 from the laser diode is transmitted within the core 100a and is outputted at the other end thereof.
Then, when the optical fiber 100 installed at the case 151 is to be removed from it, the sleeve 152 is pushed within the fixing hole 154a in a direction opposite to its pulling-out direction. That is, the knob 162 is held in such a way that it can be pushed against the optical fiber 100 in a direction parallel to it and then it is pushed until the stopper 164 abuts against the engaging step 155. A metered part 163 formed at the extremity end of the sleeve 152 pushes wide the extremity end of each of the lock claws 167 and a fitted state of the extremity end of the lock claw 167 into the covering part 100b of the optical fiber 100 and its held state are released. In this way, it is possible that the optical fiber 100 is pulled out of the case 151 under a state in which the sleeve 152 is being pushed into the case 151.
However, there was a problem in the prior art optical communication module that it was necessary to arrange a space section for the sleeve 152 moved in an inserting or removing direction of the optical fiber 100 within the case 151, a thickness of the sleeve 152 in this direction as well as a length of the sleeve 152 by itself could not be ignored, resulting in that its thin and small-sized arrangement was made difficult.